Abstract

An anthropomorphic hand arm system using variable
stiffness actuation has been developed at DLR. It is
aimed to reach its human archetype regarding size, weight and
performance. The main focus of our development is put on
robustness, dynamic performance and dexterity. Therefore, a
paradigm change from impedance controlled, but mechanically
stiff joints to robots using intrinsic variable compliance joints
is carried out.
Collisions of the rigid joint robot at high speeds with stiff
objects induce the energy too fast for an active controller to
prevent damages. In contrast, passively compliant robots are
able to temporarily store energy. In this case the resulting
internal forces applied to the robot structure and the drive
trains are reduced. Furthermore, the energy storage allows to
outperform the dynamics of stiff robots.
The hand drives and the electronics are completely integrated
within the forearm. Extremely miniaturized electronics have
been developed to drive the 52 motors of the system and
interface their sensors. Several variable stiffness actuation
principles used in the arm joints and the hand are presented.
The paper highlights the different requirements that they have
to fulfill. A first test of the systems robustness and dynamics
has been performed by driving nails with a grasped hammer
and is demonstrated in the attached video.